Hi Brian
IS-IS is considered more stable because you can manually set the refresh
time as far out as 18 + hours. Also, it is more secure, because routing
updates are transmitted via a layer 2 transport, (CLNS). Also, IS-IS can
support over 850 routers in a single area. Try doing that with OSPF, also
most enhancements that are added to OSPF are also added to IS-IS.
Russ
At 05:21 AM 11/17/2000 , Brian Lodwick wrote:
> You know sometimes the bottom of answers are so deep. It is hard to
>actually get to the bottom. Reading books from different authors I often
>notice contradicting stories. This gets to be quite confusing.
>
>Howard wrote:
>>>I wouldn't say US government requirements drove IS-IS. In fact, I'd argue
>>>to the contrary.
>
> I am currently reading Sam Halabi's Second Edition BGP book. He notes that
>"IS-IS was initially, often chosen over OSPF, because the U.S. Government
>required support of ISO CLNP by networks in order for the networks to be
>awarded federal contracts."
>
> Howard wouldn't you consider a requrement for this IGP in order to be
>awarded a Government contract, to be a driving factor?
>
>
>
> Sam Halabi then goes on to note that "folklore suggests the driving factor
>was that IS-IS implementations were much more stable than OSPF
>implementations."
>
> I wonder if over the years improvements to OSPF have caused it to become
>more popular in newer networks? I am excited to learn more about IS-IS and
>OSPF in the future. It is very cool to learn this information from someone
>with such a wealth of experience! I did not realize the difficulties we ran
>into with Europe.
>
>
>>>>Brian
>
>Go Alternet!
>
>>From: "Howard C. Berkowitz" <[EMAIL PROTECTED]>
>>Reply-To: "Howard C. Berkowitz" <[EMAIL PROTECTED]>
>>To: [EMAIL PROTECTED]
>>Subject: RE: IS-IS use??
>>Date: Thu, 16 Nov 2000 17:59:01 -0500
>>
>>>"William Gragido" <[EMAIL PROTECTED]> wrote,
>>
>>
>>
>>>IS-IS is most definetly still alive and kicking. The US military utilizes
>>>it, and it works very well. OSPF is a different animal, and Rik, I would
>>>disagree with your statement as to its scalability. IS-IS was designed to
>>>provide complete non-vendor dependent integration at the request of the US
>>>Government(ie Military), to accomadate its World Wide network.
>>
>>I wouldn't say US government requirements drove IS-IS. In fact, I'd
>>argue to the contrary.
>>
>>The direct ancestor of IS-IS is DECnet Phase IV routing, principally
>>designed by Radia Perlman. DEC contributed its work to ISO, and
>>IS-IS was initially developed as a pure OSI routing protocol (i.e.,
>>for CLNP). IS-IS became the native IGP for DECnet Phase V, which was
>>OSI (protocol, not just model) at its lower layers. This was at a
>>time when many European governments, and their PTT's that dominated
>>international standards, were very anti-IP. I am _not_ making it up
>>when I quote, from my experience in OSI standards committee, European
>>PTT people saying they would not accept a protocol suite "designed by
>>the bomb-crazed American military."
>>
>>In 1986-1988, the US government issued the Government OSI Profile
>>(GOSIP), which mandated OSI protocols for future government use.
>>Integrated IS-IS, in part, was intended as an interim protocol to use
>>while people migrated from proprietary and IP protocols to OSI.
>>
>>Of course, market forces drove the world to the IP protocol suite. I
>>hate to say IP won the war over OSI; it's more that the two
>>intermarried. The good protocol things in OSI have wound up in IP,
>>and the bad things are mostly forgotten.
>>
>>Integrated IS-IS was implemented in Alternet, Sprint, etc., partially
>>because the CLNP vs. IP debate was still a very open issue at the
>>time those networks were implemented.
>>
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Regards,
Russ Meyer
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